This invention relates generally to improvements in digital versatile disc systems and, more particularly, to a technique for enabling a DVD player to access remote data.
Digital versatile discs (DVDs) are information storage devices used for storing prerecorded audio information, movies and computer software. The storage mechanism used in DVDs closely resembles that used in compact discs (CDs). DVD players also use the same laser technology as CD players. Briefly, both DVDs and CDs store information as a pattern of pits formed in a metallic substrate. The pit patterns form digital words and can be read by shining a laser beam on the disc surface and detecting the reflected beam. The information storage capacity of a typical DVD, however, is much higher than a CD. Presently available DVDs have a variety of capacities which depend on the technology used to manufacture the discs. Single-layer technologies can be either single or double-sided with capacities of 4.7 gigabytes and 9.4 gigabytes, respectively. Dual layer technologies which use single or double sided capacities that hold approximately 8.5 gigabytes per side are available. This high information storage capacity makes DVDs suitable for storing not only audio information, but also video information and large amounts of computer data as well.
DVD players have many CD player features, such as the ability to play selections in any order desired and the ability to read information from any point on the disc. However, DVDs can store information in several formats. For example, DVDs which are used to store video information, hereinafter called DVD-VIDEO discs, may use various known information compression algorithms, such as MPEG-2 for video compression/decompression. A DVD may also include high fidelity sound as well. In addition, a DVD may also store uncompressed linear pulse code modulated data streams which have sample rates between 48-96 kHz and are sampled at 16 or 24 bits. Still other DVD versions, hereinafter called DVD-ROM discs, can store digital data for computer use, and the data may also be compressed on these discs.
Although DVD-ROM and DVD-VIDEO discs share compression algorithms, the data format on DVD-VIDEO discs is significantly different than the data format found on DVD-ROM discs. One important difference is that the data content on DVD-ROM is platform-specific, while DVD-VIDEO discs operate with a platform independent navigation engine for playing interactive movies. This navigation engine requires that the files on the DVD-VIDEO disc be referenced in a predetermined directory structure.
The specific navigational commands which are recognized by a DVD player are controlled by a device independent language and a set of DVD player parameters which define the current state of the DVD player. The DVD command set, including the aforementioned commands and their definitions, are published in the DVD specification. A copy of the DVD 1.0 Specification for Read-Only Disc Vol. 3, including a more detailed description of all DVD commands, may be obtained, for example, from Toshiba Corp., 1-1 Shibaura 1-Chome, Minato-ku, Tokyo 105-01 Japan.
The DVD specification proposes the use of ISO/IEC 13818 to combine different types of presentation data and navigation information. DVD data is arranged in packs, each consisting of at least one packet, on DVD discs. A stream identifier located within each pack header operates in conjunction with substream identifiers located within each packet to indicate the type of data contained within each packet. The DVD specification sets aside stream IDs and substream IDs for MPEG 1 audio and video packets and for MPEG 2 audio and video packets. Additionally, a private_stream_1 stream ID is used in conjunction with a set of substream IDs to identify packets that contain presentation data other than MPEG 1 or MPEG 2 audio or video data. For example, the private_stream_1 stream ID is used in conjunction with a 1010 0*** (binary) substream ID to identify linear pulse code modulated audio presentation data. Similarly, a private_stream_2 stream identifier may be combined with a set of substream identifiers to identify packets that contain navigation data.
Although the DVD specification accommodates different types of data, it only provides for the use of one source of data: the DVD disc itself. Consequently, the amount of information presentable to the user is limited to the capacity of the disc. Additionally, any updates to the presentation content or changes to the navigation structure of the content must be supplied by a new set of media. Although, instance software updates, additions to data, advertising, and on-line registration, etc. may be distributed electronically over private and public computer networks, such as the Internet, conventional DVD players cannot take advantage of such distribution channels. Consequently, a conventional DVD playback system whose navigational and presentation abilities are restricted to the immediate medium, e.g., to a DVD disc, is of limited use.
Accordingly, a need exists for a technique by which DVD, CD and other media players, which have been designed according to legacy specifications can access presentation data, software updates and other information over computer networks, such as the Internet, while still complying with the specifications to which they were designed.
The present invention provides a technique in which the DVD bitstream content enables a DVD playback system to access the Internet, or other computer networks or data sources, while still complying with the DVD specification. Specifically, the present invention contemplates the use of new navigation commands which enable a DVD browser to switch among various sources of presentation and navigation data, such as DVD discs, Internet web pages, and satellite feeds. The invention further contemplates the provision of access to the various sources of presentation and navigation data through the use of xe2x80x9cunusedxe2x80x9d program substream identifiers set forth within the DVD specification. By employing the xe2x80x9cunusedxe2x80x9d identifiers, the invention permits a DVD playback system constructed in accordance with the principles of the invention to maintain compatibility with legacy DVD systems and, at the same time, to provide access to a multitude of additional sources of presentation and navigation data. In another area of compatibility with legacy systems, the invention operates with browsers, such as internet browsers, to service presentation and navigation data originating from non-DVD compatible sources.
According to one aspect of the present invention, in an illustrative embodiment an interactive DVD browser includes DVD presentation and navigation engines which respectively operate upon presentation and navigation data. The navigation and presentation engines may obtain data, for example, from a bitstream provided by a DVD player. Data within the bitstream may be any one of several types of data, including MPEG-1 audio or video data, MPEG-2 audio or video data, Linear Pulse Code Modulated data, etc. Whatever type of data is involved, the data is arranged within packs in compliance with the DVD specification. Unused private_stream_1 and private_stream_2 substream identifiers are employed by the invention to allow an interactive DVD browser to change the source from which it is receiving navigation and presentation data, respectively. That is, the invention employs substream IDs undefined by the DVD specification, IDs that might otherwise be used to indicate that a different type of data is contained within the pack, to switch to another data source.
The interactive DVD browser (IDB) operates on predefined DVD data in a conventional manner. When the IDB encounters a user-defined DVD packet, one which the DVD spec permits a user to define, the interactive DVD browser, which contains the presentation and navigation engines, switches to a different source, a source that may be identified by the encoding of network addresses, such as Hypertext Markup Languages (HTML) addresses, within DVD packs that include the newly-defined substream identifiers.
This new source could be a DVD compliant source, e.g., a web site could emulate a DVD player, for example, to expand the content of a DVD disc. In such a case, the interactive DVD browser routes the presentation and navigation data from the new source to the IDB""s DVD presentation and navigation engines. If the new source does not have DVD compliant presentation and navigation data, the interactive browser switches navigation and presentation data from the non-DVD source to non-DVD presentation and navigation engines, engines which may be contained within an internet browser, for example. A user interface routes decoded data from one or more of the presentation engines to a user output. The user interface also routes commands from a user to one of the navigation engines.